if there are 2040 seats in a section of a stadium, 20 seats in the first row, and 4 more seats in each row, how many rows are th
ere?
2 answers:
Nth term: 16+4n
2040=16+4n
Subtract 16 from both sides
2024=4n
Divide by 4
506=n
506 rows
2040 = n/2(20+(n-1)4)
4080 = n(20+4n-4)
4080= 20n +4n^2 -4n
1020 = 4n + n^2
n^2 +4n -1020 =0
use common formula (can't write out so just look at answers. sorry)
which gives answers of n=-34 and n=30. since n can only be positive, n=30 so there are 30 rows. I liked that challenge
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